The present invention relates generally to warp-knitted textile fabrics and, more particularly, to a warp-knitted fabric knitted of an open mesh construction with selvedges adapted to resist any tendency of the side margins of the fabric to induce curling.
Many constructions of textile fabrics exhibit an inherent tendency to curl at the free edges of the fabric, which can be particularly problematic in that such curling makes the fabric difficult to wind into a uniformly cylindrical roll form and additionally makes the fabric difficult to handle, both manually and using automated machinery.
Such problems can be particularly acute with fabrics of an open mesh construction. For example, one known type of open mesh fabric is formed of a warp-knitted construction forming diamond-shaped mesh openings, which may be used for reinforcing natural or synthetic rubber products such as in the manufacture of pressurized fluid-carrying hoses (e.g. automotive radiator hoses). To render such fabrics suitable for such uses, the fabrics must be heat set, usually by transport through a tenter frame, and a suitable resin, such as melamine, must be applied as a stiffening agent to fix and retain the mesh openings in a uniform diamond shape and in uniform alignment of the openings relative to one another both lengthwise and widthwise of the fabric.
However, because of the severe tendency of the lateral lengthwise edges of the fabric to curl, it is extremely difficult in practice for the operators of tenter frames to properly feed the fabric edges onto the pins or into the clamps of a tenter frame with the mesh openings correctly aligned lengthwise and widthwise without introducing bow or bias into the lengthwise and/or widthwise alignment of the mesh openings. In practice, it has been found to be necessary not only to maintain a sufficiently low speed of the tenter frame to facilitate careful manual feeding of the fabric edges, but it has also been found to be necessary to transport the fabrics through several successive passes through the tenter frame in order to reliably eliminate bow and bias from the mesh openings in the fabric.
Specifically, in a conventional process, the mesh fabric is initially transported through the tenter frame to partially heat set the fabric sufficiently to improve its handleability, after which the stiffening resin is applied and the fabric is transported in a second pass through the tenter frame (or through a second tenter frame) to dry the resin, and then a final pass through the tenter frame (or through a third tenter frame) is made in order to fully heat set the resinated fabric. As will be appreciated, while this conventional process achieves a mesh fabric with satisfactorily uniform widthwise and lengthwise alignment of the mesh openings without bow or bias, the process is very labor-intensive, time-consuming and inefficient and, in turn, the expense of the resultant fabric is substantially increased.